1. Field of the Invention
This invention relates to solar power plants and more particularly, to a high efficiency system combining heliostats for collecting solar energy with subterranean boilers, heat exchangers and electric power generators.
2. Description of the Prior Art
Solar powered electricity generating systems are well known. One recently installed system is currently operating at a desert site near Barstow, Calif. In this system, heliostat fields of concentrating mirrors are arranged around central locations on which are placed receiving boilers. The boilers produce steam to operate turbine generators, producing an electric power output in the order of 80 megawatts. The estimated overall efficiency of the Barstow system is in the vicinity of 50%, due primarily to high thermal losses from the boiler to the turbine.
Another of the several known solar power generating systems is described in U.S. Pat. No. 3,892,433 by Floyd A. Blake. Blake discloses a fan shaped array of concentrating mirrors, mounted to track the sun and to concentrate the reflected solar rays into the aperture of an above-ground tubular boiler. The boiler produces superheated steam to drive a turbine generator. Of particular note, the system is designed to be matched with an existing hydroelectric system and augments it. The system as disclosed, does not appear to operate at a higher efficiency than prior systems, although the disclosed concentrating heliostat is an improvement. The heat losses, boiler to turbine generator, are expected to be similar to prior art installed systems.
Other patents, such as U.S. Pat. No. 4,318,393 by Richard J. Goldstein are concerned with solar energy receivers and power collection. In Goldstein's invention, a porous surface receiver and concentrator of reflected radiation is disclosed. The receiver is intended for use in a concentrating solar collector system which may be integrated with a power conversion system.
Turbine-generator systems utilizing steam, gas or high velocity water, are of course well established, as is also the case for the use of an elevated fluid storage reservoir as a hydroelectric augmentation.
Solar power electrical generating systems described heretofore in the literature or operating in installed systems include some or all of the above-described elements. However, none of the known systems include a method of subterranean processing of collected solar energy in order to increase the system efficiency. In general, all the known above-ground systems for collecting and converting solar energy suffer relatively high thermal losses at the collecting boiler to turbine or other devices.